“He just casually wrapped it in tissue, but it in an envelope and slipped it into her mailbox," adds the source. "No note, no words, just the ring." Give us a moment — we're bawling right now.

So what does this ring mean exactly?

"It was a huge statement on Rob’s part symbolizing his full forgiveness of Kristen and his renewed trust in her future,” the source says.

So perhaps another ring might not be too far off in the future — by which we mean, an engagement ring? At this rate, we wouldn't be surprised.

Rob also gave Kristen plenty of other loot on her birthday in person.

“There was the latest chain and bracelet set from Versace and a Hermès silk scarf,” says an insider. “He also managed to get a hold of an original vinyl copy of her favorite Van Morrison song, ‘Madame George.’” Aww!